Steam generator



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STEAM GENERATOR Filed Oct. 2, 1964 a Sheets-Sheet 1 a BA? ij v" E324 I A66 w INVENTOR E904 W GOGG/A/S ATTORNEYS P. W. GOGGINS A i-2R m, 1%?

STEAM GENERATOR 3 Sheets-Sheet 2 Filed (kit. 2, 1964.

INVENTOR ATTORNEYS United States Patent 3,313,275 STEAM GENERATGR PaulW. Goggins, PA). Box 936, Thomasville, Ga. 31792 Filed Get. 2, 1954,Ser. No. 401,032 8 Claims. (Cl. 122-156) This invention relates toapparatus for heating water and producing steam, and more particularly,it is directed to a steam generator which is fired by a gas or oilburner and which circulates hot combustion gases to heat water by bothconduction and convection of heat from the combustion gases,

The boilers and steam generators of the type contemplated by thisinvention are necessarily heavy and bulky because of the strongconstruction required to accommodate high temperatures and pressureswhich are to be produced within the apparatus. These characteristics ofweight and size often make it difficult to transport and install suchdevices, and the weight and size problem is especially pronounced in thecase of heavy duty industrial type steam generators.

As an example of the difliculties that may be encountered, the spacelimitations within a boiler room itself, or in the passageways leadingto the boiler room, may make it impossible to carry in a fully assembledboiler unit without making structural changes in the building itself,and once installed there is no provision for adjusting the position ofthe burner unit as related to the remainder of the unit. Usually, thepositioning of the exhaust vent and pipe fittings is determined bypre-existing service facilities at the boiler room location, but oncethese elements are positioned, there is no way to adjust the position ofthe protruding burner unit relative to the remainder of the unit.Therefore, it can be seen that it would be desirable to provide for arelative adjustment of parts of the unit after it is installed in orderto accommodate the unit to space restrictions of a given boiler roomsite.

I have provided a construction of a boiler or steam generator which ismade up of two basic components, a combustion unit and a boiler unit,which may be rotated relative to one another in order that the assembledboiler or steam generator may be more readily adapted and adjusted toexisting boiler room space conditions. This feature of adjustment allowsthe burner firing unit to be positioned in any of several positions, asrequired.

I have provided a construction which allows for the disassembly of theentire apparatus into the two basIc units so that the apparatus may bemore easily transported and handled prior to its installation at thesite where it is to be used. By breaking the entire apparatus down intotwo basic components, it is possible to move the components throughdoorways and other limited access areas which otherwise could not beeasily negotiated by the completely assembled unit. It is an importantfeature of this invention that the assembly, disassembly and relativeadjustment of the components of the boiler or steam generator can beaccomplished easily without affecting or otherwise upsetting the basicdesign of the apparatus.

In the operation of the boiler or steam generator, it is necessary toprovide for a transfer of heat from hot combustion gases into waterwhich is to be heated, and this transfer of heat is commonly effected bypassing the hot gases through tubes or coils which are dispersed throughthe water jacket of the boiler. These gases normally make only a singlesweep through the tubes or coils before they are exhausted to theatmosphere and it is therefore necessary to transfer as much heat aspos- 3,313,275 Fatented Apr. 11, 1967 sible in this single sweep inorder to avoid substantial heat losses. This is usually accomplished byconstructing the tubes of relatively thin material to permit rapidconduction of heat, but of course, this results in a relatively shortlife for the boiler or steam generator because the tubes eventually burnout from sustained use at high temperatures.

Therefore, my invention involves a vertically firing boiler or steamgenerator which is so constructed that the hot combustion gases makethree complete passes against the opposed surfaces of the boiler waterjacket, thus creating a heat pattern within the water and allowing moreof the combustion heat to be efiiciently transferred to the water.Furthermore, by creating a heat pattern within the water, a circulationpattern of the water is established which results in quicker heattransfer throughout the boiler. The fiow of the combustion gases and theconduction of heat are controlled by the used of heat control fins whichwill be described more completely in a later discussion. By eliminatingtubes and coils from the water jacket construction, this inventionprovides for an apparatus which may be constructed of stronger materialand which is less susceptible to burning out. Thus, a longer life of theentire unit is assured.

Prior tube-type boilers and steam generators have further disadvantagesin that they are costly to manufacture, and difl-lcult to clean andrepair. Periodic cleaning or flushing is necessary because of thesediment or mud which accumulates in the lower part of the water jacket,and this mud often becomes hardened and even baked onto the Walls of theWater jacket, making it difiicult to be removed by a simple flushing orwashing action.

This invention provides for a boiler or steam generator which is sodesigned and constructed that it can be easily and economicallyconstructed, maintained and cleaned. Inspection plates are providedwhich are easily removed and replaced, and access ports are included inthe design to permit flushing and cleaning of mud and sediment from thebottom portion of the water jacket.

Also, this invention provides for a mud ring portion of the water jacketwhich is insulated from the heat of the combustion gases. This separatemud ring construction allows mud and sediment to accumulate in a portionof the water jacket which is relatively cool and which prevents the mudfrom hardening and baking onto the walls of the jacket. By keeping thesediment in a soft, unhardened state, it is a comparatively simple andeconomical operation to flush the sediment from the unit during periodiccleanings.

These and other features of this invention will become apparent in themore detailed discussion which follows.

Although this invention lends itself to various possible constructionsand embodiments, it will be discussed in detail with particularreference to the preferred embodiment of a steam generator asillustrated in the accompanying drawings in which:

FIGURE 1 is a perspective view of the assembled steam generator showingthe externally attached water and steam fittings, gauges and controldevices which are not a part of the present invention;

FIGURE 2 is a perspective view of the assembled steam generator withsections cut away to show detail of the generator and to show the pathof flow for hot combustion gases through the generator;

FIGURE 3 is a perspective view of the steam generator with the outerinsulating shell removed to show detail of heat control fires, and withthe upper boiler unit spaced from the lower combustion unit;

FIGURE 4 is a detail perspective view of one of the support bracketswhich join the lower combustion unit to the upper pressure unit;

FIGURES 5 through 7 are sectional top views of the steam generator toshow three possible relationships between the two basic units of thesteam generator;

FIGURE 8 is a sectiontal side view of the assembled steam generator;

FIGURE 9 is a top view of the supporting structure associated with theend plates; and

FIGURE l0 is an enlarged sectional side view of upper and lower endplates which are a part of the upper boiler unit. This view is taken at10-19 of FIGURE 9.

As shown in FIGURES l-3 and 8, the steam generator of this invention ismade up of two basic units, a combustion unit 10 and a pressure unit 12.

The combustion unit 10 is made up of any suitable ceramic material 14having an outer steel shell 16 and this unit serves as a base for theassembled steam generator. The combustion unit is provided with an inlet13 which connects an externally attached gas or oil burner 20 to aninternal combustion chamber 22. The gas or oil burner 20 may be of anysuitable electrically driven forced draft type of burner which deliversfuel to the combustion chamber 22 where it is ignited and burned. Thecombustion chamber 22 is generally cylindrical in shape but isconstructed with inwardly tapered walls 24 near the top of the chamberso that heat will be reflected and concentrated back into the centralpart of the chamber, thereby providing a better ignition of and a morecomplete burning of gases in the combustion chamber. An uppermostextension 26 of the combustion unit 10 provides for a communicationbetween the lower combustion unit 10 and the upper pressure unit so thathot combustion gases can pass into a central firing tube 28 which is apart of the upper pressure unit 12. This extension 26 is defined by anupwardly extending wall portion 29 ofsinsulating material which extendsfrom the upper face 30 of the combustion unit 10. The extension 26serves to insulate a portion of the lower water jacket for a purposewhich will be discussed in greater detail later. Additionally, theextension 26 serves as an aligning means for assisting in the alignmentof the combustion unit with the pressure unit when the steam generatoris being assembled or rotated.

The pressure unit 12 is removably mounted on the combustion unit 10, andthis may be accomplished with any suitable mounting means such assupport braces 31 which provide for an easy assembly and disassembly ofthe two basic units 10 and 12.

With reference to FIGURES 24, it can be seen that the four supportbraces 31 are equally spaced around the lower perimeter of a waterjacket 32, which is a part of the upper pressure unit 12. The supportbraces 31 include base portions 34 and upright wall portions 36 whichare rigidly secured to each other at right angles and which arereinforced by means of the upright bracing walls 38. These supportbraces are permanently afiixed to an outside wall portion 40 of thewater jacket 32, such as by welding the upright wall portion 36 of thesupport brace to the outside wall portion 49 of the water jacket. Whenproperly affixed, the support braces 31 will be equally spaced from oneanother around the lower periphery of the water jacket, and the baseportions 34 of the support braces will project outwardly from thecentral longitudinal axis of the upper pressure unit 12.

The support brace 31 is also provided with a bore 42 through the baseportion 34 and this bore is adapted to receive a threaded stud or bolt44 which may be used to removably secure the upper pressure unit 12 tothe lower combustion unit 10. Suitable bores are provided on the upperface portion 30 of the lower combustion unit 10 for receiving the studs44, and these bores of the combustion unit 10 are positioned to line upwith the bores 42 of the support braces 31 when the upper pressure unit12 is placed on the lower combustion unit 10. The studs or bolts 44 maybe threaded into the lower combustion unit or otherwise affixed so as toleave a threaded end exposed in order that nuts may be used to attachthe upper pressure unit to the lower combustion unit. In this manner,the threaded studs 44 may be permanently afiixed in position within thebores 46 of the combustion unit and the upper pressure unit 12 may thenbe lowered into position with the support braces properly aligned formating assembly with the studs 44. From that position, the two basicunits may be tightly secured by turning nuts 48 (FIGURE 1) downwardlyonto the threaded ends of the studs 44 until a tight coupling of the twounits is accomplished.

It can be appreciated that this means of coupling provides for a steamgenerator unit which can be easily disassembled for transporting or forcarrying through con fined spaces to a boiler room site. It can befurther appreciated that it is a comparatively simple and easy task toreassemble the two basic units into a complete unit without affectingthe design or function of the unit.

It is also a feature of this invention to provide for an adjustment ofthe lower combustion unit 10 relative to the upper pressure unit 12 oncethe steam generator iP located at the boiler room site where it is to beused. The desirability of this feature becomes obvious when it isrealized that the upper pressure unit part of the steam generatorcarries with it all fittings for service connections to exhaust vents,water inlets and outlets, steam outlets and other necessary connectionsto make the steam generator operational. In accordance with thisinvention, the upper part of the steam generator is positioned to mosteffectively provide for a connection of these service connections toexisting facilities, and the lower combustion unit portion of the steamgenerator is then rotated to a position where the protruding burner 20is best fitted to the space requirements of the particular site. Withthe use of four support braces as described above, the base unit may berotated at a time, thus providing four possible positions for theprotruding burner as related to a given position of the upper pressureunit. Three possible positions are shown in FIGURES 57 where the burnerposition 22 is rotated with respect to an exhaust vent 49. Of course, itis contemplated that the addition of more support braces with an equaladdition of mating positions on the base unit would provide forincrements of adjustment of less than 90", if such finer adjustmentshould be required.

Turning now to the specific construction of the pressure unit asillustrated in FIGURES 2, 3 and 8, it can be seen that the pressure unit12 includes a water jacket 32, a water and steam reservoir 50 which isan extension of the water jacket, heat flow control fins 52, and serviceconnections (not shown) for a water inlet, a steam outlet and an exhaust49 for combustion products. The water jacket and heat exchange portionsof the pressure unit are enclosed within a cylindrical insulating shell54 which is cast from any suitable insulation material 55 and this shellis covered with a steel jacket 56.

The water jacket 32, and the steam and water reservoir 50 together formthe boiler 58 of the steam generator of this invention. The water jacketportion and the reservoir portion are essentially integral and providefor a ready circulation of water throughout the entire boiler. Theboiler 58 contains the water to be heated together with steam producedfrom the water, and of course, the boiler is constructed from materialwhich can withstand the temperatures and pressures developed within atypical steam generator. Pipe means are provided for conducting waterinto the boiler and for carrying steam out for ultimate consumption, butthese pipes and other necessary control devices are not a part of thisinvention and will be understood by those skilled in the art to beassociated with this invention.

With particular reference to FIGURE 8, the water jacket 32 has an innerwall 62 and an outer wall 40. The inner wall 62 defines the centralfiring tube 28 and is in direct contact with the hot combustion gasesrising from the combustion chamber 22. The outer wall 40 defines theouter perimeter of the entire boiler 58. The bottom plate 64 of thewater and steam reservoir forms a closed end wall to the central firingtube 28, and thus the hot combustion gases are prevented from making asingle straight-' through sweep in their passage from the combustionchamber 22 to where they are exhausted to the atmosphere. An end wall 65at the bottom of the water jacket defines the bottom end of the boiler58, and a top wall 67 of the reservoir forms the top end of the boiler.

The water jacket 32 is further provided with a plurality of access ports66 through the outer wall 49, and these access ports are for purposes ofinspecting and cleaning the interior of the water jacket. Similar accessports 63 are provided in the wall 70 of the water and steam reservoir 50in order that the reservoir may also be conveniently inspected orcleaned. Of course, the access ports 66 and 68 are provided withclosures and are kept closed during operation of the steam generator.The closure means may be any suitable means for providing a tight sealagainst the high temperatures and pressures generated by the boilerunit.

As shown in FIGURES 2 and 3, the boiler 58 is provided with fouropenings 60 which are arranged at 90 degrees from one another at theuppermost portion of the water jacket 32. The openings 60 serve as exitsfor hot combustion gases from the central firing tube 28 in order thatthese gases may be caused to make a series of passes through the steamgenerator, as will be described more fully later. It will be appreciatedthat the openings 60 must be completely sealed from the water zonewithin the water jacket since the hot combustion gases never directlycontact the water to be heated in a steam generator of this type. Such asealing is accomplished by the wall portions 61 which span the spacebetween the inner and outer walls of the water jacket. The Wall portions61 fOIIIta conduit through the water jacket through which the hot gasesmay pass. Of course, it is contemplated that a greater or lesser numberof openings may be utilized than the four shown in the preferredemobdiment. The outer wall 40 of the water jacket is provided with heatcontrol fins 52 which serve to control the convective fiow of hot gasesover the outer surface of the boiler, and which also serve to conductheat from the hot gases into the water within the water jacket. The fins52 are of several lengths as shown in FIGURE 3 and are permanentlyafiixed to the outer wall 49 of the water jacket, as by welding.

All of the fins terminate at a common level at their lower ends and thislower termination is at a point which is well above the lowermost levelof the water jacket itself. The upper ends of the fins terminate atvarying levels depending upon the particular function and location ofthe individual fins.

Looking to FIGURE 3, the shortest length fins 72 extend longitudinallyalong the outer wall 40 of the water jacket from points even with thelower edges of the openings 69 down to the common lower terminus of allfins, indicated at 73. These shortest length fins 72 are shown as beingarranged in groups of five and these groups are located at spacedintervals below each of the openings 69. Each separate group covers awidth of the outer wall surface 40 which is approximately equal to thewidth of one of the openings 60. Thus, there is provided a path for hotcombustion gases which are exiting from the openings 64) to traveldownwardly along the outside surface of the water jacket along equallyspaced sections of the wall as defined by the fins 72. The hotcombustion gases are deflected downwardly upon leaving the openings 60by any suitable deflection means associated with the openings 60. Suchdeflection means have been shown as bafiles 69 which are located abovethe openings 69 and which prevent the hot gases from rising when theyexit from the openings. The intermediate length fins 74, which are alsoarranged in groups of five, provide a controlled-width path for a finalpass of the hot gases upwardly along the outer surface of the boiled.The spaced locations of the groups of fins '74 alternate with the spacedlocations of the groups of fins 72 as shown in FIGURE 3. The fins 74 arelonger in length than the fins 72 so that heat may be conductedthroughout their entire length into the water jacket 32. The upperterminating points of the fins 74 are approximately even with the levelWhere the reservoir adjoins the water jacket 32, and the lower terminusof the fins 74 is common with all of the fins at 73.

The longest fins 76 are arranged singly between the groups of fins 72and 74 so as to maintain a separation of the downwardly flowing hotgases in the paths defined by the groups of fins 72 from the upwardlyflowing gases in the paths defined by the groups of fins 74. The fins 76extend longitudinally up along the lower part of the reservoir 50,however, they do not cover the entire length of the reservoir because itis essential that the gases, upon reaching the top of the boiler aftertheir final sweep past fins 74, will be free to travel around the outercircumference of the boiler wall to an exhaust vent 49, shown as adotted circle in FIGURE 8.

It is a feature of this invention that the flow paths for the hotcombustion gases are so arranged that a scrubbing or cleaning actiontakes place by the action of the hot gases moving through the steamgenerator in the series of passes described above. The scrubbing actionis accomplished by decreasing the size of each subsequent path as thegases move from the central firing tube to their ultimate exhaustion tothe atmosphere. Thus, it will be appreciated that the volume of space inthe combined downward flow paths defined by the groups of fins 72 isless than the volume of space in the central firing tube. Likewise thevolume of space in the combined upward flow paths defined by the groupsof fins 74 is less than the volume of space in the paths of fins 72. Bythis arrangement, the velocity of the gases is increased as the gasespass back and forth through the steam generator, and as a result thereis a cleaning action which helps prevent a buildup of carbon deposits onthe walls of the boiler.

The final element of the assembled pressure unit 12 comprises aninsulating shell 54 which extends around the boiler unit from the top ofthe water and steam reservoir 549 down to a level which stops above thelowermost portion 80 of the water jacket. The portion 80 of the waterjacket will hereinafter be termed the mud ring since it is that part ofthe water jacket where sludge and sediment settle out from the waterwhich is being heated. It is apparent that the insulating shell 54contacts and cooperates with the fins 52 of the water jacket to hold asmuch heat as possible within the heat conductive zones of the boilerunit thereby assuring a greater efificiency in transferring heat fromthe hot combustion gases into the water which is being heated togenerate steam. The insulating shell 54 has an outer steel jacket 56 andan inner insulating layer 55 cast from any suitable insulation material.It can be seen that the inner insulating layer 55 extends for the entirelength of the insulating shell 54. However, the thickness of theinsulation layer is less at the top portion 82 which surrounds the waterand steam reservoir 55) than it is in the lower portion 84 whichsurrounds the water jacket and its associated fins.

The top portion 82 of the insulation material is thinner than at theremainder of the insulating shell because the combustion gases at thislevel are ready to be exhausted to the atmosphere and are much coolerthan the initial temperature in the central firing tube; therefore thereis less reason to retain heat in this area of the generator. Anadditional reason for the thinner wall of insulation at 82 resides inthe necessity for providing a space 85 for the circumferential movementof the combustion gases around the reservoir 50 and out of the exhaustvent 49.

The lower portion 84 of the insulation material of the shell 54 isthicker than the portion 82 to provide greater efficiency in retainingheat against the heat conductive portions of the water jacket 32. Also,it can be seen that the thickness of insulation in the portion 84 mustbe sufficient to effectively prevent any circumferential movement ofgases around the water jacket 32 in the region of the fins 52. Bycontacting the outer edges of the fins 52 with the insulation layer 84,there is provided an effective seal between the fins and the insulationlayer, and the insulation layer 84 then serves to cooperate with thefins 52 to confine the flow of gases over the outside surface of thewater jacket.

The insulation layer 84 extends downwardly along the longitudinal axisof the water jacket to a point which is beyond the lower terminus of thefins 52 in order to provide a space 88 for gases to turn from theirdownward flow and to begin their upward flow along an adjacent group offins. However, it is important that the insulation layer not extend overthe region of the water jacket which is termed the mud ring 80 becausethe mud ring is purposely insulated from heat as much as possible inorder to prevent sludge and sediment from hardening and baking onto theinterior walls of the water jacket, as is common in prior generators ofthis type.

The insulating shell 54 is further provided with upper end plates 90 andlower end plates 92 which serve to form end walls for spaces 86 and 88respectively. These end plates 90 and 92 are arranged in segments aroundthe top and bottom ends of the insulating shell 54 and are easilyremovable to provide for inspection of the spaces between the boilerunit and the insulating shell. In addition to serving as removableinspection plates, the end plates 90 and 92 also act as baflles atopposite ends of the gaseous fiow paths and serve to turn the fiow ofgases when gases strike them.

The attachment of the end plates 90 and 92 to supporting structures canbe seen in greater detail in FIG- URES 9 and 10. In FIGURE 9, thesupporting structure 93 for the top end plate 99 is shown in a top viewas having an inner band 94 and an outer band 96 spaced from the innerband. The inner band 94 is of such a size as to be affixed around thetop of the reservoir section 50 of the boiler. The outer band 96 isattached to the steel jacket 56 of the insulating shell 54, and bracketmembers 98 are interposed at spaced points between the inner and outerbands 94 and 96 as shown in the view in FIGURE 9.

The inner band 94 is provided with means 100 for tightening the bandonce the supporting structure 93 is positioned around the boiler unit.The tightening means 100 may be any suitable screw device, or the likefor drawing together the ends 162 and 104 of the inner band 94. It willbe appreciated that prior to tightening the band 94 a sufficient gap 106exists between the ends 102 and 104 of the inner band to allow a finaltightening of the band around the boiler unit.

A similar supporting structure is provided for the bottom end plates andthe relative positions of the top and bottom supporting structures isillustrated in FIGURE taken at 10-10 of FIGURE 9. When in positionaround the boiler unit, the supporting structures provide means 108 forremovably attaching the top and bottom end plates in their properpositions against the top and bottom perimeter respectively of theinsulating shell 54. Attaching means 108 may be threaded studs or boltsadapted to receirgg nuts 110, and a stud 108 is associated with eachbracket member 98. Thus, end plate segments (as illustrated by top platesegment 90, FIGURE 9) may be threadedly secured across bracket members98, and when removed the spaces 89 and 88 between the boiler unit andthe insulating shell may be readily inspected and/or cleaned. In thepreferred embodiment of this invention, an insulating layer 112 isplaced between the supporting members 93 and the attached end plates inorder to provide for better retention of heat within the steamgenerator. The insulating layer 112 may be made in segments tocorrespond to the end plate segments, thus providing for a ready removalof both the end plate segment and its associated insulating layersegment 112.

Having described the details of construction of the steam generator, theoperation of the generator may now be discussed.

Initially, the unit is installed and adjusted, as described above, toprovide the desired relationship between the positions of the combustionunit 10 and the pressure unit 12. After the steam generator is fullyinstalled and operational, hot combustion gases are produced by thefiring of fuel delivered by the burner unit 29 into combustion chamber22. The hot gases rise upwardly through the central firing tube 28, andin this first pass through the length of the boiler unit, heat isconducted through the inner wall 62 of the water jacket 32 into thewater which is to be heated. When the hot gases reach the uppermostpoint of the central firing tube, they are deflected outwardly by thewall 64 of the water and steam reservoir. It will be appreciated thatthe reservoir wall 64 forms an end wall to the central firing tube 28,and as the hot gases strike the end wall in their upward pass throughthe boiler unit, heat is transferred directly into the water in thereservoir. Thus, in the first pass through the steam generator, heatfrom the hot combustion gases is given up to water in the water jacketportion of the boiler and to water in the reservoir portion of theboiler as well. It should be noted at this point, that during theinitial pass through the steam generator all of the hot gases arecompletely surrounded by water. The gases are at their hottesttemperature during this first pass, and it is safer and more efficientin a steam generator to surround these hottest gases as much as possiblewith water jacket portions.

Since the reservoir Wall 64 forms an end wall to the central firingtube, the hot combustion gases are deflected outwardly through theplurality of openings 60 situated through the uppermost section of thewater jacket 32. Upon exiting outwardly from the openings 60, the hotcombustion gases are now deflected downwardly along the-outside wall ofthe water jacket 32. The bafiie structure 69 spaced around the outerwall 70 of the reservoir 50 at intervals above each of the openings 60,prevents the hot combustion gases from rising as they are deflectedoutwardly from the openings 60. Thus, the downward deflection of thegases at spaced intervals around the outside wall of the water jacket isassured, as shown by the flow arrows in FIGURES 2, 3 and 8.

The hot gases fiow downwardly in this second pass through the steamgenerator along paths defined by the shortest heat control fins 72. Asdescribed earlier, the heat control fins serve to conduct heat into theinterior of the water jacket. In addition, the fins cooperate with theinsulating shell 54 to control the convective flow of the hot gasesalong the length of the outside wall of the water jacket. Since theoutside edges of the heat control fins contact the inside wall of theinsulating shell 54, an effective seal is formed, and it is impossiblefor the hot gases to flow transversely around the perimeter of theboiler in the region of the fins. In this manner the flow of gases canbe controlled to make a series of longitudinal passes along a major partof the boiler, and greater heat conduction and efliciency of operationare accomplished.

The downward flow of hot gases takes place at spaced intervals aroundthe outside wall of the water jacket as determined by the groups of fins72 which are grouped below the spaced openings 60. *Upon reaching thelower terminus 73 of the fins 72, the gases continue downwardly into thespace 88 until they strike the lower end wall formed by lower end plates92 and their associated insulation segments 112. The lower end platesact to seal the hot gases within the steam generator unit, and the gasesare therefore deflected transversely around the lower outside wall ofthe Water jacket.

The hot gases are prevented from returning up the path defined by thecontrol fins 72 because the pressure of additional hot gases comingdownwardly along that path continually forces the gases along in theirmovement through the steam generator. Also, the transverse deflection ofthe hot gases around the lower space 88 is limited by the presence ofother gases having completed their downward passes along the downwardpaths defined by the fins 72 under each of the four openings 69.Therefore, the gases from all of the downward passes turn upwardly alongthe paths which alternate with the downward pass paths. These upwardpaths are located at spaced intervals defined by the groups ofintermediate length fins 74, and it is along these paths that the hotgases make a third and final pass, along the major length of the outsidewater jacket wall. The third pass conducts additional heat to the waterin the water jacket, providing a high degree of efficiency in obtainingheat from the hot combustion gases which originated in the combustionchamber 22.

In addition to the eificiency obtained by causing the hot gases to makethree complete passes along the length of the water jacket, anadditional advantage in this construction lies in the heat patternswhich are formed in the water jacket. The three passes of hot gasesagainst the water jacket are made at varying temperatures since thegases give up heat during each pass. Thus, there is formed a heatpattern in the water jacket which includes a balanced temperature in thecentral tube and with the outer wall being hot in sections and cooler inothers. This creates circulating cycles of water movement, which arecounterflow to the gas movements. The heat patterns established on thewater jacket create a novel water circulation pattern which insures ahigher rate of heat exchange and a greater efficiency in steamgeneration.

Another feature of the preferred construct-ions provides a scrubbingaction of the gases in their passage throughout the steam generator.This scrubbing action results from the provision of narrower paths to befollowed by the gases in each subsequent passage in the series ofpassages through the generator. It will be noted that the central firingtube is of a greater volume than the combined volumes of the fourdownward paths and likewise the combined volume capacity of the fourdownward paths is greater than the total volume of the four final upwardpaths. Thus, as the gases progress in their travel throughout the steamgenerator, pressure and velocity are increased, and this provides ascrubbing action which maintains the steam generator in a cleaner, moreeflicient operating condition at all times.

When the hot gases have completed their final upward pass, as describedabove, they enter the upper space 86 surrounding the reservoir 59, andthey make their way transversely around the top of the reservoir 50 tothe exhaust vent 49 provided for carrying gaseous combustion products tothe atmosphere. It should be noted that even in this final pass aroundthe reservoir prior to being exhausted, the gases may conduct additionalheat into the boiler by conduction through the wall 70 of the reservoir.

It is desirable in steam generators of this type to be able toperiodically inspect and clean the unit, as required. For that purpose,the removable top and bottom end plates 99 and 92, respectively, areprovided for an inspection or cleaning of the spaces between the outerwall of the boiler 58 and the inner wall of the insulating shell 54. Adetailed description of the end plates 90 and 92 was given above in thediscussion of FIGURES 9 and 10.

Further access to the unit is provided by the hand holes or access ports66 located in the lower water jacket section described as the mud ring80, and these access ports 66 may be opened for cleaning of the mud ringsection by fiushing or by any other suitable method. As described above,the mud ring section 81) of the water jacket is substantially insulatedfrom the hot combustion gases of the 10 generator, and therefore thesludge and sediment which settle into the mud ring section remain in asoft state and are more easily removed. The insulation of the mud ringinner wall is provided by the extending wall portion 29 of the lowercombustion unit 10, and the outer wall of the mud ring is insulated byan absence of the heatretaining insulating shell 54 in the region of themud ring.

The access ports 68 have been described as located in the wall 70 of thewater and steam reservoir 50, and these ports provide for inspection andcleaning of the upper sections of the boiler unit 58. Also, it ispossible to use the access ports 68 in cooperation with the lower ports66 for back flushing scale and sediment from the entire boiler,including the mud ring.

The access ports 68 are normally not visible from the outside of theassembled unit, and are made accessible only by the removal of a panelelement of the outer steel jacket 56, as at 120. The panel of the outerjacket 56 may be mounted for easy removal by any suitable means such asby spring clips or the like. FIGURE 1 shows two panels 120 in place, anda third one is removed to show one of the access ports 68 with itsclosure in place.

Having described the construction and operation of the steam generatorof this invention, it can be seen that the objects of this inventionhave been fully met. It is contemplated that variations of the abovedescribed preferred embodiment will become obvious to those skilled inthe art, and such variations may be made without departing from thescope of this invention.

I claim:

1. A steam generator comprising a combustion unit for burning fuel and aboiler unit for heating water from the heat of said burning fuel, saidboiler unit including a water jacket portion for holding water to beheated by conduction and a reservoir portion for storing heated waterand steam, said water jacket portion and said reservoir portion being incommunication with one another for circulation of water between the twoportions; said water jacket portion comprising an inner wall and anouter wall, said inner wall forming a firing tube in open communicationwith said combustion chamber so that hot combustion gases may pass fromthe combustion chamber unit into the water jacket portion of the boilerunit; an end Wall in said water jacket portion common to the reservoirportion and forming a closed end to the central firing tube whereby saidcentral firing tube is completely surrounded by water retaining walls; aplurality of radial discharge openings through said water jacket portionlocated near the closed end of said central firing tube therebyproviding exits for hot combustion gases which have been deflected bythe closed end wall of said central firing tube after completing a firstpass through said boiler unit, deflection means associated with saidouter wall of said water jacket portion for turning the hot combustiongases as they exit from said radial discharge openings whereby saidgases are caused to make a second pass through said boiler unit througha first plurality of spaced paths extending substantially the entirelength along said water jacket portion outer Wall, additional deflectionmeans associated with said outer wall of said water jacket portion forturning said gases upon completion of the second pass through saidboiler unit whereby said gases are caused to make a third pass throughthe boiler unit along a second plurality of spaced paths on said waterjacket portion outer wall, said second plurality of spaced paths beingalternated with said first plurality of spaced paths so that acounter-flow of hot gases is established between adjoining paths; heatcontrol means associated with said outer wall of said water jacket forpromoting a more rapid conduction of heat into the water to be heatedand for directing the flow of hot gases along the outside wall paths ofsaid water jacket; and insulating means cooperating with said deflectionmeans and said heat control means for confining heat to selected.portions of said boiler unit ll 1 whereby a heat pattern is establishedin the water jacket portion of said boiler unit.

2. A steam generator according to claim 1 where said heat control meanscomprise heat-conductive fin elements attached longitudinally to theouter wall of the water jacket.

3. A steam generator according to claim 1 where said water jacketportion further includes a mud ring portion for receiving scale andsediment settling out from the water which is being heated, and aninsulation barrier for maintaining the mud ring portion of the boilerunit at a cooler temperature than the remainder of the water jacketportion, whereby scale and sediment settling in said mud ring portionwill remain in a soft, unbakedstate for easy removal from the waterjacket.

4. A steam generator according to claim 3 where said insulation barriercomprises an extension portion of material from said combustion unit,said extension portion being interposed between the burning fuel and themud ring portion of said water jacket portion.

5. A sectional steam generator comprising a combus tion unit for burningfuel and a boiler unit for heating water from the heat of said burningfuel, attachment means for removably securing the combustion unit to theboiler unit so that the two units may be easily assembled, disassembledand rotated relative to each other; said boiler unit including a waterjacket portion for holding water to be heated by conduction, and areservoir portion for storing heated water and steam, said water jacketportion and said reservoir portion being in communication with oneanother for circulation of water between the two portions; said waterjacket portion comprising an inner wall and an outer wall, said innerwall forming a firing tube in open communication with said combustionchamber so that hot combustion gases may pass from the combustionchamber unit into the firing tube of the water jacket portion; an endwall in said water jacket portion common to the reservoir portion andforming a closed end to the central firing tube whereby said centralfiring tube is completely surrounded by Water retaining walls; aplurality of radial discharge openings through said water jacket locatednear the closed end of said central firing tube and providing exits forhot combustion gases which have been deflected by the closed end wall ofsaid central firing tube after completing a first pass through saidboiler unit, deflection means associated with said outer wall of saidwater jacket for turning the hot combustion gases as they exit from saiddischarge openings whereby said gases are caused to make a second passthrough said boiler unit along substantially the entire length of afirst plurality of spaced paths on said water jacket outer wall,addition deflection means associated with said outer wall of said waterjacket for turning said gases upon completion of the second pass throughsaid boiler unit whereby said gases are caused to make a third passthrough the boiler unit along a second plurality of spaced paths on saidwater jacket outer Wall; said second plurality of spaced paths beingalternated with said first plurality of spaced paths so that acounter-flow of hot gases is established between adjoining paths, heatcontrol means associated with said outer wall of said water jacket forpromoting a more rapid conduction of heat into the water to be heatedand for directing the flow of hot gases along the outside wall paths ofsaid water jacket, and insulating means cooperating with said deflectionmeans and said heat control means for confining heat to selectedportions of said boiler unit whereby a heat pattern is established inthe water jacket portion of said boiler unit.

6. A sectional steam generator according to claim 5 where said heatcontrol means comprise heat-conductive fin elements attachedlongitudinally to the outer wall of the water jacket portion.

7. A sectional steam generator according to claim 5 where said waterjacket portion further includes a mud ring for receiving scale andsediment settling out from the water which is being heated and aninsulation barrier for maintaining the mud ring of the water jacketportion at a cooler temperature than the remainder of the water jacketportion, whereby scale and sediment settling in said mud ring portionwill remain in a soft, unbaked state for easy removal from the waterjacket.

8. A sectional steam generator according to claim 7 where saidinsulation barrier comprises an extension portion of material from saidcombustion unit, said extension portion being interposed between theburning fuel and the mud ring portion of said water jacket.

References Cited by the Examiner UNITED STATES PATENTS 940,427 11/ 1909Chambers 122-382 1,349,617 8/1920 LaFoy 122155 1,754,102 4/1930 Harding122155 1,850,678 3/1932 Landvoigt 122214 2,287,376 6/1942 Furlong et al.122-382 2,374,707 5/1945 Scharpe 122-16O 2,580,033 12/1951 Loweth et a1122-214 2,627,252 2/1953 Mohn 122-494 X 2,761,430 9/1956 Schacfer l22494X KENNETH \V. SPRAGUE, Primary Examiner.

1. A STEAM GENERATOR COMPRISING A COMBUSTION UNIT FOR BURNING FUEL AND ABOILER UNIT FOR HEATING WATER FROM THE HEAT OF SAID BURNING FUEL, SAIDBOILER UNIT INCLUDING A WATER JACKET PORTION FOR HOLDING WATER TO BEHEATED BY CONDUCTION AND A RESERVOIR PORTION FOR STORING HEATED WATERAND STEAM, SAID WATER JACKET PORTION AND SAID RESERVOIR PORTION BEING INCOMMUNICATION WITH ONE ANOTHER FOR CIRCULATION OF WATER BETWEEN THE TWOPORTIONS; SAID WATER JACKET PORTION COMPRISING AN INNER WALL AND ANOUTER WALL, SAID INNER WALL FORMING A FIRING TUBE IN OPEN COMMUNICATIONWITH SAID COMBUSTION CHAMBER SO THAT HOT COMBUSTION GASES MAY PASS FROMTHE COMBUSTION CHAMBER UNIT INTO THE WATER JACKET PORTION OF THE BOILERUNIT; AN END WALL IN SAID WATER JACKET PORTION COMMON TO THE RESERVOIRPORTION AND FORMING A CLOSED END TO THE CENTRAL FIRING TUBE WHEREBY SAIDCENTRAL FIRING TUBE IS COMPLETELY SURROUNDED BY WATER RETAINING WALLS; APLURALITY OF RADIAL DISCHARGE OPENINGS THROUGH SAID WATER JACKET PORTIONLOCATED NEAR THE CLOSED END OF SAID CENTRAL FIRING TUBE THEREBYPROVIDING EXITS FOR HOT COMBUSTION GASES WHICH HAVE BEEN DEFLECTED BYTHE CLOSED END WALL OF SAID CENTRAL FIRING TUBE AFTER COMPLETING A FIRSTPASS THROUGH SAID BOILER UNIT, DEFLECTION MEANS ASSOCIATED WITH SAIDOUTER WALL OF SAID WATER JACKET PORTION FOR TURNING THE HOT COMBUSTIONGASES AS THEY EXIT FROM SAID RADIAL DISCHARGE OPENINGS WHEREBY SAIDGASES ARE CAUSED TO MAKE A SECOND PASS THROUGH SAID BOILER UNIT THROUGHA FIRST PLURALITY OF SPACED PATHS EXTENDING SUBSTANTIALLY THE ENTIRELENGTH ALONG SAID WATER JACKET PORTION OUTER WALL, ADDITIONAL DEFLECTIONMEANS ASSOCIATED WITH SAID OUTER WALL OF SAID WATER JACKET PORTION FORTURNING SAID GASES UPON COMPLETION OF THE SECOND PASS THROUGH SAIDBOILER UNIT WHEREBY SAID GASES ARE CAUSED TO MAKE A THIRD PASS THROUGHTHE BOILER UNIT ALONG A SECOND PLURALITY OF SPACED PATHS ON SAID WATERJACKET PORTION OUTER WALL, SAID SECOND PLURALITY OF SPACED PATHS BEINGALTERNATED WITH SAID FIRST PLURALITY OF SPACED PATHS SO THAT ACOUNTER-FLOW OF HOT GASES IS ESTABLISHED BETWEEN ADJOINING PATHS; HEATCONTROL MEANS ASSOCIATED WITH SAID OUTER WALL OF SAID WATER JACKET FORPROMOTING A MORE RAPID CONDUCTION OF HEAT INTO THE WATER TO BE HEATEDAND FOR DIRECTING THE FLOW OF HOT GASES ALONG THE OUTSIDE WALL PATHS OFSAID WATER JACKET; AND INSULATING MEANS COOPERATING WITH SAID DEFLECTIONMEANS AND SAID HEAT CONTROL MEANS FOR CONFINING HEAT TO SELECTEDPORTIONS OF SAID BOILER UNIT WHEREBY A HEAT PATTERN IS ESTABLISHED INTHE WATER JACKET PORTION OF SAID BOILER UNIT.